Pediatric lymphomatoid papulosis: a broad clinicopathologic spectrum including rare variants in a single-center case series.

Background: Lymphomatoid papulosis (LyP) is a rare CD30-positive cutaneous T-cell lymphoproliferative disorder, extremely uncommon in children and adolescents. Despite its indolent course, LyP may mimic malignant lymphomas clinically and histopathologically, making diagnosis challenging in pediatric patients. Objectives: To characterize the clinical, histopathologic, immunophenotypic and molecular features of pediatric LyP and to describe treatment approaches and clinical outcomes. Methods: We performed a retrospective observational study of pediatric patients with clinicopathologically confirmed LyP evaluated at our tertiary referral center between 2004 and 2025. Demographic, clinical, histopathologic, immunophenotypic, molecular, treatment and follow-up data were collected. Results: Nine patients were included (8 males, 1 female), with a median age at diagnosis of 11 years (range 2-18). Lesions predominantly involved the limbs (9/9, 100%), followed by the trunk (5/9, 56%) and hands (4/9, 44%). Ulceration or necrotic evolution occurred in 6/9 patients (67%). Type A was the most common histologic subtype (5/9, 56%), followed by single cases of types B, D, E and one overlap A-C case. CD30 expression was observed in all patients. T-cell receptor clonality was identified in 4/5 tested cases. Management was mainly conservative, consisting of topical corticosteroids and phototherapy (nbUVB or PUVA). Methotrexate was used in one patient. At the last follow-up, all patients were free of active LyP lesions, and no associated hematologic malignancy was documented. Conclusions: Pediatric LyP shows heterogeneous clinicopathologic features with overall favorable outcomes. However, long-term follow-up remains warranted due to the lifelong risk of associated lymphoproliferative disorders.